hopwood



J. M. HOPWOOD. FUEL SUPPORT FOR FURNACES.

APPLICATION FILED AUG. I3, 1918- Patented Oct. 21, 1919.

3 SHEETS-SHEET I.

J. M. HOPWOOD. FUEL SUPPORT FOR FURNACES.

APPLICATION FILED AUG, I3. ISII].

Patented Oct. 2t, 1919.

3 SHEETS-SHEET 2- wrm ES'ISE'IS J. M. HOPWOOD. FUEL SUPPORT FORFURNACES. APPLICATION FILED AUG.I3. I9I8.

1 ,3 1 9, 584;. Patented Oct. 21, 1919.

3 SHEETS-SHEET 3.

gyzawww WWW-mm UNITED STATEENT OFFICE.

JOHN M. HOPWOOD, 0F DORMONT, PENNSYLVANIA, ASSIGNOR TO DARWIN S.WOLCOTT, TRUSTEE, 0F SEWICKLEY, PENNSYLVANIA.

FUEL-SUPPORT FOR FURNACES.

instance,

Specification of Letters Patent.

Patented Uct, 21, 191%.

Application filed August 13, 1918. serial No. 249,729.

To all whom it may concern:

Be it known that 1, JOHN M. Horwoon,

residing at Dormont, in the county of All egheny and State ofPennsylvania, a citizen of the United States, have invented ordiscovered certain new and useful Improvements in F uel-Supports forFurnaces, of which improvements the following is a specification.

Dilliculty is experienced in the use of the type of fuel supportingsurfaces consisting of bars extending in the direction of movement ofthe fuel in the furnace and spaced to permit of the flow of air betweenthem into the fuel, due to the fact that the bars will grow or increasein dimensions when maintained for a considerable time at hightemperatures. When placing these bars in position in the furnace, twoconditions which to a considerable extent. are opposed, one to theother, must be reconciled as far as possible, 2'. 6., the bars must bespaced a sufficient distance apart to permit of the passage of airbetween them in sufficient quantities to support combustion, and on theother hand provision should be made to prevent the sifting of fine coal,ashes, etc., in material quantities between the bars. While theseconditions can be fulfilled to a practically efficient degree when thebars are new, the transverse growth of the bars due to continuedmaintenance at a high temperature will so reduce the spaces between thebars that sufficient air cannot pass between the bars, even if thepressure of air be increased to an undesirable degree, and if the growthis great the bars will contact one with the other requiring greaterpower to effect their movements.

The invention described herein has for its object the maintenance ofspaces of suflicient areas between adjacent members forming the fuelsupporting surfaces to insure an efficient supply of the flow of air tosupport,

combustion at low pressures and at the same time to prevent the slftmgof fine coal and ashes down between the bars and the avoidance of anyliability of adjacent bars coming into contact. It is a further objectof the invention to provide a regulation of the supply of air forcombustion in accordance with the condition of the fuel bed. The invention is hereinafter more fully described and claimed.

lln the accompanying drawings forming a part of this specification,Figure 1 is a sectional view of the furnace for a boiler havlng myimprovements embodied therein; Figs. 2, 3, at and 5 are transversesections on an enlarged scale, of two main bars and an auxiliary bar andillustrating respectively different forms embodying improvements claimedherein; Fig. 6 is a view partly in side elevation and partly in sectionof one of the forms of the auxiliary bars; Fig. 7 1s a longitudinalsection of the same; Fig. 8 is a View similar to Fig. 1 and having oneof the series of bars movable for regulating the supply of air to thefuel bed; Fig. 9 is a detail View showing in sid elevation an auxiliaryand a main bar, the former having progressively reduced air feedinggrooves;

and Fig. 10 is a sectional view on an enlarged scale the plane ofsection being indicated by the line X-X, Fig. 8.

While the improvement is shown and described in connection with gratebars having non-connected longitudinal passages with inlets and outletsat the respective ends of such passages, through which the air forsupporting combustion flows into the air chambers under the grate barsand up between adjacent grate bars, it will be understood that theimprovemcnts claimed herein can be readily used in combination withother forms or types of bars.

in the construction shown, the grate bars 1 are constructed with twolongitudinal assages a and 5, each extending approximately half thelength of the bars and each provided with openings or ports adjacent. totheir ends. These ports are connected with supply chambers and withboxes or chambers 2 below the bars into which the air is dischargedafter passing through the bars and from whichthe air will flow upthrough the spaces between the bars.

These bars are supported at their ends and preferably intermediate oftheir ends by any suitable means and in such manner that the bars ifdesired may be reciprocated longitudinally to effect the progressivemovement of the fuel.

In order to prevent any material amount spaces and overlap the adjacentbars as par-.

ticularly shown in Fig. 5. Although portions of the main and auxiliarybars overlap, provision is made whereby there may be a full free flow ofair between the bars and into the fuel bed regardless of the growth ofthe bars. It will be preferable in most cases to. employ auxiliary barshaving webs 4 adapted to extend down between adjacent main bars as shownin Figs. 2 and 3, in

which case the thickness of the. webs and the spaces between the mainbars are so proportioned as to afford ample spaces for the upward flowof air. The flow of air between the overlapping portions of the mainbars and the bridge or auxiliary bars,

' can be provided for either by so supporting the latter that there maybe passages which will not be closed by growth between such overlappingsurfaces, or grooves 5 may formed in one or both of such overlappingsurfaces. In order that the growth"of the bars forming the fuel supportsdue to long continued excessive heating, may not detrimentally reducethe air spaces between the webs 4 and the sides of the main bars,grooves 6 are formed in at least one of the adjacent walls of the bars,and preferably in the side walls of the webs 4, the grooves 6 being inalinement with grooves 5 in the overlapping surfaces of the bars. Thisgrooving of one orb'oth of the adjacent faces of the main and auxiliarybars will insure a flow of air into the fuel regardless of any growth.As shown in Figs. 1 and 2, the upper sides of the main bars may be madeflat and the bridging or auxiliary bars which bear thereon, projectingabove the upper surfaces of such main bars, or recesses 7 may be formedalong the edges of the main bars 'for the reception of'the bridging orauxiliary bars, as shown in Figs. 3, 4 and 5. The latter constructionwill be generally advantageous as the bridging bars may not pro- Qjectup into the fuel bed and hence will not be subjected to excessiveheating.

It will be observed that fine coal, ashes, etc, mustbefore dropping downbetween the bars, pass between the bridging and main bars; such movementwhich will be at an angle to the general movement of fuel and ashes willbe prevented by the flow of air outwardly between the overlappingportions of the bars. It will be also observed that air flowing ubetween the bars, will flow in opposite cirections in thin streams orjets into the fuel, thus assuring a more uniform distribution of the airthrough the bed of fuel. s

As is well known, the greatest amount of air is required where there isthe greatest generation of gases, 2'. 6., adjacent to the point wherethe fuel is charged onto the grate surface, and that as the fuel ismoved through the furnace to the point of discharging the ashes, smallervolumes of air are required. Such a distribution of air may be effectedby making the grooves 5 adjacent to the front end of the furnacecomparatively large and progressively smaller toward the rear ends ofthe fuel supporting surfaces as shown in Fig. 9.

In lieu of effecting a proportional distribution of air to the bed offuel by different dimensions of air passages, such distribution can beeffected, by shifting one series of bars forming the fuel supportingmeans relative to those of the other series, as shown in Figs. 8, 9, and10. A convenient means for adjusting one series of bars to vary the airsupply, consists in connecting the series of bars to be shifted atpoints adjacent to their front ends, to arms 8 on a shaft 9 arrangedtransversely of the fuel supporting surface, such connection beingconveniently formed by links 10. The rotation of the shaft to raise themovable bars can be effected by any suitable means such as a Worm 11engaging a worm wheel 12 secured on the end of the shaft projectingoutside of the furnace as shown in Fig. 10. The movement of the bars issimilar to that of a 1ever having its fulcrum at the rear ends of themovable bars and hence the spaces between the shifted and stationarybars will 7 be greatest at the front of the furnace. In addition toproportioning the supply of air,

the employment of shiftable bars as described will permit of regulatingthe supply of air to the entire bed of fuel, increasing or decreasingsuch supply as conditions may require.

In order to prevent fine coal and ashes from dropping between thestationary bars, when the movable bars are reciprocated, the webs 4 areextended sufficiently beyond the heads or bridging bars so as to projectunder the fore plate of the furnace as shown at 13- in Figs. 8 and 9.

Either one or both of the series of bars maybe reciprocated to advancethe fuel along the supporting surface as shown in Figs. 1 and 8. Asuitable reciprocating mechanism consists of levers 15 having one endconnected to the plungers 16 of the stoking mechanism and their oppositeends isiaee i connected by pitmen 17 to one end of levers 18 which havetheir opposite ends engaging the main rate bars.

When the series of main grate bars are reciprocated, the bridging orauxiliary bars are held from movemcnt'with the main bars in any suitablemanner, such for example as that shown in Fig. l. The webs of thebridging bars which are extended under the dead plate 19 are providedwith notches 20 adapted to engage the bar 21 arranged transversely ofthe furnace under the dead plate.

\Vhen the main bars are reciprocated and the bridging or auxiliary barsare held stationary, as described, the latter cannot be extended ontothe curved rear portions of the main bars and hence provision is madefor closing the spaces between the main bars beyond the points where theauxiliary bars terminate. A convenient means to that end consists ofplates 22 fitting into recesses in the ends of the main bars andbridging the spaces between adjacent main bars. When the bridging orauxiliary bars are reciprocated as shown in Fig. 8, the spaces betweenthe main bars at the rear ends of the latter are closed by fillingpieces to prevent the passage of ashes.

I claim herein as my invention:

1. In a furnace the combination of spaced main grate bars extending inthe direction of movement of fuel in the furnace and auxiliary barscarried by the main bars and so bridging the spaces between the mainbars as to maintain regardless of growth predetermined spaces for thepassage of air flowing up between the main bars into the fuel bed andpreventing a sifting of fine material into the spaces between the mainbars.

2. In a furnace the combination of spaced main grate bars extending inthe direction of movementof fuel inthe furnace and auxiliary barsbridging the spaces between the main bars and having portionsoverlapping and supported by adjacent main bars, adjacent overlappingsurfaces being provided with means to insure, regardless of growth, afree'discharge into the fuel of air flowing up between the main bars. m

3. In a furnace the combination of spaced main grate bars extending inthe direction of movement of fuel through the furnace, and auxiliarybars bridging the spaces between the main bars and having portionsoverlapping and supported by. adjacent main bars, adjacent portions ofoverlapping surfaces being constructed to efi'ect a proportionaldistribution of air flowing up between the main bars into the fuel,

a. In a furnace, the combination of a fuel support consisting ofa'series of grate bars extending in the direction of movement of fuelthrough the furnace and spaced to permit of the flow of air between theminto the fuel, a second series of grate bars adapted to bridge thespaces between the bars of the first series and spaced from the latterto maintain a predetermined minimum flow of air into the fuel incombination with means to shift the bars of one series relative to thoseof the other series to permit of a flow of air greater than normal intothe fuel.

5. In a furnace, the combination of a series of spaced main grate barsand a series of auxiliary bars bridging the spacesjbetween the main barsand so spaced therefrom as to permit of predetermined minimum flow ofair into the fuel, means for reciprocating one of the series of bars andmeans fol-shifting the bars of one series relatively to those of theother series and thereby permit of a flow of air greater than normalinto the fuel.

6. In a furnace the combination of spaced main grate bars and auxiliarybars, said bars extending in the direction of movement of fuel in thefurnace, portions of the auxiliary bars overlapping adjacent main barsand supported thereby and having portions projecting between the mainbars and said bars being so constructed that when arranged in operativerelation in a furnace air will flow between the bars and into the fuelsupported by the latter.

7. In a furnace the combination of a series of spaced main grate barsextending in the direction of movement of fuel through the furnace and aseries of auxiliary bars T-shaped in' cross section alternating with themain bars and supported thereby, adjacent surfaces of one of the seriesof bars being grooved.

8. In a furnace the combination of a series of spaced main grate barsexmnding in the direction of movement of fuel through the furnace, aseries of auxiliary bars bridging the spaces between and supported bythe main bars and having portions projecting between the main bars andadjacent surfaces of one of the series of bars being grooved, and meansfor reciprocating one of the series of bars in the direction of itslength.

9. In a furnace, the combination of spaced main grate bars extending inthe direction of the movement of fuel through the furnace and auxiliarybars bridging the spaces between the main bars and having portionsprojecting between the main bars, the main and auxiliary bars havingadjacent portions so constructed that spaces of a predetermined minimumcapacity for the passage of air into the fuel will be maintained betweensuch adjacent surfaces of the main and auxiliary bars.

10. In a furnace, a series of grate bars having therebetween spacespermitting a maximum growth of the bars while maintaining apredetermined minimum of air spaces and means for bridging the. bar

spaces to prevent material discharge of coal and bridging means beingconstructed to maintain therebetween, regardless of the growth of thebars, a predetermined minimum of space for the flow of air into thefuel.

In testimony whereof I have hereunto set my hand.

JOHN M. HOPWOOD.

